[ Upstream commit b26322d2ac6c1c1087af73856531bb836f6963ca ]

The function should return an error if create_singlethread_workqueue()
fails.

Fixes: 34877a15 ("net: stmmac: Rework and fix TX Timeout code")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>